A U.S. Air Force team has conducted a technical inspection of a military airfield in Estonia, which will likely be used as a new basing alternative for NATO’s Baltic Air Policing mission.

Airmen from the 48th Air Expeditionary Group RAF Lakenheath recently visited Amari Air Base in Estonia to certify the base’s aircraft arresting system, seen as a critical step toward validating the airfield as a new NATO forward operating base, a news release on Friday said.

NATO’s Baltic Air Policing mission was set up a decade ago to patrol the skies over Estonia, Latvia and Lithuania, which don’t have fighter aircraft of their own. NATO countries take turns sending contingents of about four warplanes to respond to any airspace violations. Currently, the mission consists of four USAF F-15s, which were beefed up by an additional six fighters after the outbreak of the crisis in Ukraine.

Polish air force MiG-29s are scheduled to take over from the F-15s next month. Because of the continuing crisis, they will be backed up by British Typhoons and Danish F-16s.

Since 2004, the NATO mission has operated from the Lithuanian air base at Siauliai. But more recently, Estonia has offered the Amari as a second base for the air policing element.

The arresting system on an airfield is similar to the one on an aircraft carrier. An aircraft that has brake problems or other trouble stopping lowers it tail hooks to catch a cable strung across the runway, which gradually slows the jet to a complete stop. Emergency crews then assist the pilot and shut down the plane’s engines.

NATO has said it will rotate more ships, planes and troops to Eastern Europe to reassure allies, but it shied away from new permanent bases in the east. The media in Scandinavia have speculated that the Danish F-16s could be based at the temporary base in Estonia.

The U.S. Army is currently deploying about 600 troops from the Vicenza-based 173rd Infantry Brigade Combat Team to Poland and Baltic nations for training with allied forces. A company-size unit of about 150 servicemembers is going to each of the four nations.

Officials in those countries hailed the U.S. decision to increase its military presence in order to reassure regional allies in the wake of Russia’s takeover of Ukraine’s Crimean Peninsula.

“The US presence provides, on one side, a visible reassurance, and on the other, an opportunity to intensify training and deepen interoperability,” said a statement by Poland’s Defense Ministry. “Thus, we see that as a vehicle for development of more structural, long term approach to bilateral defense cooperation and, more broadly, to a consolidation of [the] Alliance’s position in the region.”